Solar Sizing Guide: How Many Panels Do You Actually Need?

Solar sizing gets treated like guesswork more often than it should be. It isn't — it's a straightforward calculation once you know your daily energy use and your panel's real output. Here's how to get it right, whether you want a quick pre-matched answer or want to size a custom setup yourself.

The Quick Answer: Our Pre-Matched Packages

If you'd rather not run the numbers yourself, our three Off-Grid Packages are pre-sized around real usage patterns:

• Weekend Escape: 7.1kWh battery + 5000W inverter + 2× 460W solar panels — short getaways, basic to moderate load
• Touring: 16.1kWh battery + 5000W inverter + 4× 460W solar panels — extended trips needing faster recharge
• Full-Time: 16.1kWh battery + 5000W inverter + 5× 460W solar panels — maximum solar input for continuous off-grid living

The Formula: Sizing a Custom Setup

If your usage doesn't fit neatly into one of those tiers, the calculation itself is simple:

Panels Needed = Daily Wh Used ÷ (Panel Wattage × Peak Sun Hours × System Efficiency)

Breaking down each part:

Daily Wh Used

Use our Battery Sizing Calculator to get a real daily Wh figure based on your actual appliances.

Panel Wattage

OzX supplies the TCL 460W N-Type Back Contact panel — a commercial-grade panel, not a standard consumer panel. The N-Type back contact design places the cell contacts on the rear of the panel instead of the front, which removes the front-surface busbars that cause shading losses on conventional panels. Combined with a genuine 23.1% module efficiency, this means more usable output across the day — including the lower-angle morning and afternoon periods where standard panels lose more of their output to shading and reflection.

Peak Sun Hours

Most of Australia sees roughly 4–5.5 peak sun hours per day on average, depending on region and season — this is the industry-standard baseline for solar calculations, representing the equivalent hours of full-intensity sunlight in a day. Because OzX panels harvest more efficiently across the full daylight period (not just the peak window), real-world output tends to sit toward the higher end of what a standard panel would deliver under the same conditions.

System Efficiency

Account for real-world losses — wiring, connector resistance, temperature derating, and charge controller conversion — typically in the 80–85% range for a well-installed system.

Worked Example

Say your daily use comes to 3,000Wh (a typical extended-touring load per our calculator). Using one 460W panel, 5 peak sun hours, and 80% system efficiency:

460W × 5 hours × 0.80 = 1,840Wh per panel, per day

3,000Wh ÷ 1,840Wh = 1.6, rounded up to 2 panels — which lines up with the Weekend Escape package's solar allocation for a similar load profile.

Frequently Asked Questions

How many solar panels do I need for full-time off-grid living?
Our Full-Time package uses 5× 460W panels alongside a 16.1kWh battery, sized around continuous daily solar recovery rather than relying on periodic mains charging.

Does panel efficiency actually matter, or is wattage all that counts?
Efficiency matters for real-world output, not just the rated number. A higher-efficiency, back-contact panel like the TCL 460W captures more usable energy across the day — including lower-light periods — than a standard panel with the same wattage rating.

Can I add more panels later if I undersize initially?
Check your inverter's solar input voltage range before adding panels in series — the DCX 5000W inverter is available in 60–120V and 120–450V input variants, so your available headroom depends on which model you have.

What happens on cloudy days?
Solar output drops significantly in overcast conditions. This is exactly why battery capacity and solar array are sized together, not solar alone — your battery is there to cover the gap when solar input drops.

Should I round up or down when sizing?
Round up. Running short on solar input off-grid is a bigger inconvenience than carrying one extra panel.

Use the Battery Sizing Calculator to get your real daily Wh figure, or explore the Off-Grid Packages for a pre-matched solution.